我们可以使用字典中的键调用该值
class mymodel(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super().__call__(*args, **kwargs)
return cls._instances[cls]
class mytest(object,metaclass=mymodel):
pass
检查其属性
mytest._instances
{}
第一次调用mytest
,让它包含属性_instances
mytest()
<__main__.mytest object at 0x7f3286774b20>
mytest._instances
{<class '__main__.mytest'>: <__main__.mytest object at 0x7f3286774b20>}
type(mytest._instances)
<class 'dict'>
mytest._instances.keys()
dict_keys([<class '__main__.mytest'>])
使用键调用其值:
mytest._instances[<class '__main__.mytest'>]
File "<stdin>", line 1
mytest._instances[<class '__main__.mytest'>]
^
SyntaxError: invalid syntax
mytest._instances["<class '__main__.mytest'>"]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: "<class '__main__.mytest'>"
尝试用反斜杠\
转义:
mytest._instances[\<class '__main__.mytest'\>]
File "<stdin>", line 1
SyntaxError: unexpected character after line continuation character
mytest._instances["\<class '__main__.mytest'\>"]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: "\\<class '__main__.mytest'\\>"
那么如何用key调用mytest._instances
中的值呢
当您查看mytest.\u实例时,它会向您显示字典包含的内容:
也就是说,dictionary键是mytest的类,dictionary值是mytest的特定实例
因此,您可以使用以下方法获取值:
这不是字符串,而是类对象
你应使用:
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